Heater



FIG. 1 is a front view of a heater showing my new design;

FIG. 2 is a rear view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a perspective view thereof.

The broken line showing of the screws, the screw openings and the handle is for the purpose of illustrating environmental structure and forms no part of the claimed design. 

The ornamental design for a heater, as shown and described. 